1. Technical Field
The present invention relates to semiconductor packaging structures. More particularly, the present invention relates to an image sensor package structure with improved structural reliability.
2. Description of Related Art
With the rapid progress of technologies, popularization of multimedia devices is accelerated. In addition, when a large number of digital imaging apparatuses, such as digital still cameras, digital video cameras, and digital scanners, have been introduced to the market in recent years, image digitization has become an inevitable trend. One of the crucial elements that makes the digital imaging apparatuses work is the image sensor. It serves to receive and convert optical signals or image signals into electric signals, and transmit the electric signals to a circuit board for analysis, enabling a digital imaging apparatus to photograph.
In order to meet the market demand for digital imaging apparatuses to be as compact as possible, the used image sensor nowadays is typically a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or the like. Therefore, the possibility of downsizing digital imaging apparatuses relies on the technology in packaging the image sensors into minimized image sensor package structures.
Such packaging technology is preferably applicable to mass productions with lower material costs. In addition, the packaging technology should provide appropriate protection to the sensitization area on an image sensor that is extremely sensitive and might be adversely affected by external dust and moisture so as to improve the imaging performance of the image sensor and enhance the reliability of the resultant package structure. Moreover, the service life is maximized and the quality of the digital imaging apparatus is ensured.
However, the liquid compound conventionally used by the traditional packaging technology to package image sensors for preventing moisture invasion is very expensive and leaves the overall material costs of the existing image sensor package structure high. Moreover, the constantly changing processing temperature during baking tends to cause the volatile gases in the liquid compound to burst or create crevices in the baked compound. As a result, the image sensor is likely to be invaded by moisture. When the image sensor package structure later receives a reliability test, the moisture will expand and increase the pressure inside the image sensor package structure, thus resulting in damage to the image sensor and significantly reducing the production yield and reliability of the image sensor package structure.